High molecular weight air drying organic film-forming polymers and coating compositions are well-known in the art. However, because of the high molecular weight and resulting high viscosity of compositions containing these film-forming polymers, high molecular weight polymers are generally utilized in organic solvent solution coating compositions at about 40 percent by weight, exclusive of any pigment which might be present. The use of such a relatively low polymer solids content, therefore requires a relatively high content of solvent, and solvents are expensive, add cost to shipping per area of substrate coated, and offer a possible fire hazard.
The reaction of bis-carbodiimides with bis-carboxylic acids has been used by Iwakura et al. [(Polymer Letters, 6, 517-522 (1968)] to prepare poly(N-carbamoylamides). The preparation of organic polymers containing repeating carbodiimide groups has been reported by several workers. See Campbell et al J. Org. Chem., 28, 2069-2075 (1968), and U.S. Pat. No. 2,853,473. However, these do not suggest the production of unsaturated, curable polymers.